Hormone transduction and transmembrane signalling processes in general are rapidly advancing, challenging, and important areas of research in cellular and molecular biology. The molecular structures of several hormones or neurotransmitter receptors have been deciphered with realistic prospects that the molecular basis for ligand binding and action shortly will be understood. Transduction or coupling proteins that interact with receptors are in the process of being analyzed for their structure and function. New signal-generating systems in membranes have been recently discovered that account for many of the actions of hormones on such fundamental processes as calcium translocation as well as cell growth and differentiation. In essence, new revolutionary concepts are emerging to explain the pleiotropic actions of hormones and neurotransmitters on their target cells. In addressing these subjects, this application requests support for an International Symposium on Signal Transduction in Biological Membranes (Sept 3-7, 1986) which will consider: (1) the molecular structure of receptors; (2) the structure and function of GTP-regulatory proteins in transduction processes initiated by hormones, neurotransmitters, and light; (3) the role of kinases and phosphatases in regulation of signal generating processes and in the processing of membrane generated signals; (4) the mechanisms involved in production of inositol phosphates and in the actions of the latter on calcium levels in cells; (5) the means by which transmembrane signalling and signal processing can explain the behaviour of neuronal cells; and (6) the relationship between oncogenes and the regulatory processes (including receptors, GTP-regulatory proteins) involved in receptor mediated transmembrane processing and cellular transformation.